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C. P. STEINMETZ. ELECTRICAL WINDING. APPLICATION FILED NOV. 21, 1914.

1,1 94,090. Patentea Aug. 8, 1916.

Ill/ll M I I P Witnesses: Inventor: CHar-Ies S inmetz smiw;

Z 4- His aqttorneg stri rns PATENT OFFICE.

CHARLES r. s'rnmmn'rz, or scirnivnccmnr, NEW YORK, ssxenon TO GENERALELECTRIC COMPANY. A CORPORATION or new YORK.

ELECTRICAL WINDING.

Specification of Letters Yatent.

Patented Aug. 8, 191.6.

To all whom may concern:

Be it known that I, Cnannns 1 STEIN METZ, a citizen. of the UnitedStates, residing at Schenectady, in the county of Schenectady, State ofNew York, have invented certain new and useful Improvements inElectrical ll indings, of which the following is a specification.

My invention relates to electrical wind ing's for substantially allkinds of electrical apparatus, but particularly to those fortransformers.

The object of my invention is'to so arrange the coils of electricalwindings that abnormal frequencies may not build up disastrously highvoltages in resonating groups thereof.

My invention from one aspect is an improvement in an embodiment of theinvention of Elmer E. F. Creighton, disclosed in his application, SerialNo. 874,068, filed on or about Nov. 25, 1914;.

As has been recognized prior to my invention, abnormally high.frequencies may give rise to disastrously high voltages *Withinanelectrical Winding, if there happens to be accessible to the highfrequency av sec tion of the winding Whose natural frequency.

or harmonic thereof, is equal. to the ab normal frequency. The value ofthe voltage developed by a given application of a resonating frequency,is dependent upon thevalue' of the energy in the resonating section ofthe winding, and hence resonance in one or more of the groups into whichit is generally necessary to assemble the coils of a large winding, isparticularly dangerous since the amount of energy therein is necessarilygreat.

My invention is to protect windings against the d igers of resonatinggroups of coils. Broadly, I provide the different, or at least adjacent,groups of coils with such different natural frequencies that thefrequency at which one group oscillates can not readily pass over othergroups.

In carrying out my invention I assemble I the coils of awinding intogroups as here tofore,,but with unequal numbers of coils pergroupinstead of equal numbers of coils per group, as has been the commonprac tice. Thecoils may be similar in all respects to those nowemployed, in which case my invention'may be embodied in new apparatus atsubstantially no increase in the cost of manufacture thereof. The coilsof any one group may or may not all be alike, whence the groups may ormay not contain equal numbers of turns per group other conditions maydictate, but in case t icy are given equal numbers of turns, care mustbe taken that the tendency to change the frequency of the groups, due tothe differentnumbers of coils per group, is not overcome by thenecessary differences between the coils. The

tendency of different numbers of coils per group to bring aboutmaterially different natural periods for the groups is, however,

so great that there is little likelihood of its being effectivelyneutralized by the differences between the coils.

Preferably each two adjacent groups are composed. of different numbersof coils. This arrangement, whereby each two adjacent groups savematerially different natural periods, provides for damping orrestraining by interference the oscillation of each group, whether theresonating frequency is produced therein or transmitted thereto overanother group by a continued application of the frequency from outsidethe resonating group. Preferably also each end or terminal group iscomposed of a different, generally smaller, number of coils than are therespective inner groups. This latter rangement whereby the outer groupshave higher natural frequencies than the inner groups, serves best toprevent or restrain the entrance of abnormal frequencies to the innercoils from outside the winding, where the greatest number of abnormalfrequency disturbances arise. The outer groups may be more heavilyinsulated thanthe others, if necessary, since they are ii'nmediatelyaccessible to resonating frequencies produced outside the apparatus.

In the accompanying drawing, which forms a part of this specification, Ihave illustrated diagrannnatically in elevation, a shell typetransformer embodying my invention.

My invention is here shown embodied in the high voltage winding only,but it will be understood that it is not thus limited. The middle leg ofthe core 1 carries the windings. The low voltage winding made up ofseven separate coils 28. The high voltage winding is made up ofthirtysix winding, each group being between two low voltage coils. Thecoils of each winding are connected in series. The first group A. of thehigh voltage winding comprises four coils, the second B and fourth D sixcoils each, the third C eight coils, and the fi'fth group E and thesixth group F seven and five coils respectively. The coils may or maynot be made up of equal numbers of turns and thus the groups may or maynot comprise unequal numbers of turns. .Each two adjacent groups havedifferent natural frequencies and the two terminal groups have highernatural frequencies than the inner groups.

While I have described the principle of my invention, and the best modeI have contemplated for applying its principle other modifications willoccur to those skilled in this art and I aim in the appended claims tocover all modifications which do not involve a departure from the spiritand scope of my invention.

hat I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. An electrical winding comprising a pluality of coils assembled ingroups, the adjacent groups thereof comprising different numbers ofcoils to restrain the building up of dangerously high voltages throughresonance.

2. An electrical winding comprising a plurality of coils assembled ingroups, said groups having different numbers oi. coils to restrain thebuilding up of dangerously high voltages through resonance.

An electrical winding comprising a plurality of coils connected inseries and assembled in more than two groups, each of the two terminalgroups comprising a dillerent number of coils than the inner groups torestrain the building up of dangerously high voltages through resonance.

4. In a transformer, a winding comprising a plurality of electricallyconnected coils assembled in groups and a second winding separating thesaid groups, adjacent groups comprising unequal numbers of coilsrespectively, to restrain the building up of dan-v gcr-ously highvoltages through resonance.

In witness whereof, I have hereunto set my hand this 24th day ofNovember, 1914. CHARLES P. STEINMETZ. Witnesses Josnrn IIAYDEN, BENJAMINB. HULL.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents.

Washington, D. C.

